Yes it is much better than sand, is the simple answer.
Yes it is also much more expensive than sand.
It's actually spellt
Zelbrite and that's probably why you couldn't find any information on it if you have been trying.
It's not a hoax. The product really is amazing and will stand up to all the manufacturer's claims and over the longer term will save you a lot of money in water treatment, even if you are not using a saltwater chlorinator.
If you are using a big filter which holds 150Kg of sand, you could get away with using 75% by weight of Zelbrite because it is so efficient you don't need so much.
7,000 baht would sound about right.. It's sold by the importers in Bangkok in 25 kg bags at around 1,000 baht a bag, so your builder isn't making much profit on it.
However, that size filter would usually be used for a pool of around 100,000 litres and that's not a small pool. That's about 8 x 12 or 5 x 20 at an average depth of 1m. A small domestic pool is considered to be a 4 x 10 or less, which is less than half that.
Verdict: It could be that your pool builder has sold you double the pump/filtration capacity you need - this happens quite regularly, both Thai and foreign builders in Thailand operate this scam - to make more money on their mark up for supplying the equipment. So your contractor
has made a big profit on your pool.
Check Jazzman's main article about pools here, it contains a direct link to the
Zelbrite website:
http://coolthaihouse.com/forum/viewtopic.php?t=645
You could also try mailing these people:
poolandspa@ultratran.com
They are British pool and building consultants in Thailand but they give a lot of free expert advice.